How bleach kills germs

Bleach is the king of microbe killers, but before now no one knew quite why. Researchers report today in the journal Cell that bleach – like heat – kills bacteria by making proteins fall apart.

A team of molecular biologists from the University of Michigan, Ann Arbor found that hypochlorous acid (bleach's active ingredient) unravels protein chains, which then clump together in a useless mess much the way proteins do when exposed to heat or fever in the body.

Understanding how bleach works could lead to new ways to fight disease. The human body naturally makes its own hypochlorous acid to fend off microbial attackers, but a surplus has been associated with age-related diseases such as arthritis, stroke, and Alzheimer's disease.

Getting back to basics: New disease treatments may years down the road, but in the meantime a spray bottle of bleach can help kill germs before they wreak havoc. The Food and Drug Administration says a teaspoon per quart of water (or about 5 mL bleach per liter water) should keep your kitchen countertops microbe-free.